1. Field of the Invention
The present invention relates to a thin-film magnetic head with a perpendicular magnetic recording structure, to a magnetic head assembly with the thin-film magnetic head, to a magnetic disk drive apparatus with the magnetic head assembly, and to a manufacturing method of a thin-film magnetic head with a perpendicular magnetic recording structure.
2. Description of the Related Art
There are two types of thin-film magnetic heads, thin-film magnetic heads with a horizontal or in-plane magnetic recording structure used for recording magnetic information by using magnetic fields parallel to a recording medium plane and thin-film magnetic heads with a perpendicular magnetic recording structure used for recording magnetic information by using magnetic fields perpendicular to a recording medium plane. The latter perpendicular magnetic recording type thin-film magnetic heads hold great promise because they can provide stably high recording density.
The perpendicular magnetic recording type thin-film magnetic head has, near its surface facing a magnetic recording medium, a multi-layered structure with a main pole layer, an auxiliary pole layer forming a return-path of magnetic field, and a nonmagnetic gap layer sandwiched between the main pole layer and the auxiliary pole layer. The main pole layer and the auxiliary pole layer are magnetically coupled with each other at a back position in a height direction that is in a direction back away perpendicularly from an air-bearing surface (ABS). A write coil layer is embedded in a nonmagnetic insulation layer surrounded by a magnetic path loop of the main pole layer and the auxiliary pole layer. A write magnetic field produced by feeding current through the write coil layer is perpendicularly applied from a top end of the main pole layer to a perpendicular magnetic recording layer of the recording medium, passed through a soft magnetic backing layer of the recording medium, and then returned to the auxiliary pole layer. Thus, perpendicular magnetic recording to the recording medium is performed at the position opposed to the main pole layer.
In some such perpendicular magnetic recording type thin-film magnetic heads, in order to increase the write magnetic field contributing to magnetic recording, a step or a two-level portion with a slope inclined with respect to a lamination plane is formed on each surface of the main pole layer and the auxiliary pole layer opposed to each other near the ABS.
By forming such step, the write magnetic field component toward a magnetic recording medium is increased but the diffused magnetic field component toward the track-width direction is also increased. The latter lateral magnetic field component may cause adjacent track erasing (ATE) phenomenon that will erase recorded magnetic information on the adjacent tracks to occur.
U.S. Pat. No. 4,656,546 discloses a vertical magnetic recording arrangement with a downstream magnetic shield or a side shield that is formed at a tip of a write pole near its side section in the track-width direction to be exposed to the ABS in order to absorb fringing flux. By forming this side shield, although it is not a problem of inducing ATE phenomenon, a problem of inverting information already recorded on the same track on a magnetic medium can be prevented from occurring.
However, the side shield disclosed in U.S. Pat. No. 4,656,546 greatly decreases the write magnetic field itself. Also, forming of such side shield requires an additional manufacturing process causing the fabrication method to complicate.